| Abstract: | Time-resolved polarized Fourier transform infrared spectroscopy (FTIR) is employed to analyse the segmental orientation and mobility of achiral bent core molecules in response to an external electric field. By shearing the substance between ITO coated CaF2 windows two types of domain, racemic and homochiral, are formed in the high temperature B2 phase. Each of these domains is characterized by two spontaneous symmetry-breaking instabilities which yield a symmetric and an antisymmetric electro-optical response, respectively. Taking advantage of the specificity of IR spectroscopy, this switching behaviour is analysed on a molecular level for the moieties of the bent core liquid crystal materials. In this way, the electrically induced reorientation of the different segments on a cone and the suppression of the antiferroelectric structure at higher frequencies can be followed in detail. Furthermore the biased rotation of the two carbonyl groups around the molecular long axis is determined. It is shown that all molecular units move synchronously on the time scale of the experiment (10mus). |
